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United States Patent |
5,647,818
|
Moody
|
July 15, 1997
|
Shifter interlock for an automatic transmission
Abstract
An automotive shifter interlock in which a slidable shift lever release
member is mechanically locked in a shift-release-inhibit position by the
combination of an electromagnet bolt and an ignition switch bolt. The
ignition switch bolt mechanically locks the electromagnet bolt in a
position locking the shift lever release member even though no power is
supplied to the electromagnet. After the ignition switch is closed and the
ignition switch bolt withdrawn, the electromagnet continues to provide an
electromagnetic lock until the brake pedal is depressed.
Inventors:
|
Moody; John W. (Clarkston, MI)
|
Assignee:
|
Pontiac Coil, Inc. (Waterford, MI)
|
Appl. No.:
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410909 |
Filed:
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March 27, 1995 |
Current U.S. Class: |
477/99; 70/248; 74/473.24; 192/222; 477/96 |
Intern'l Class: |
F16H 059/74; F16H 063/36 |
Field of Search: |
74/477,473 SW
477/99,96
192/4 A
70/248,254
|
References Cited
U.S. Patent Documents
4473141 | Sep., 1984 | Mochida.
| |
4887702 | Dec., 1989 | Ratke et al. | 192/4.
|
4936431 | Jun., 1990 | Shinpo | 74/473.
|
4955935 | Sep., 1990 | Katayama | 192/4.
|
4986399 | Jan., 1991 | Gokee | 192/4.
|
5027931 | Jul., 1991 | Ratke et al. | 192/9.
|
5035156 | Jul., 1991 | Roble | 70/248.
|
5052509 | Oct., 1991 | Dzioba | 74/477.
|
5076114 | Dec., 1991 | Moody | 74/501.
|
5129494 | Jul., 1992 | Rolunski | 192/4.
|
5133436 | Jul., 1992 | de Crouppe et al. | 192/4.
|
5176231 | Jan., 1993 | Moody et al. | 192/4.
|
5211271 | May., 1993 | Osborne et al. | 477/96.
|
5275065 | Jan., 1994 | Ruiter | 74/483.
|
Primary Examiner: Marmor; Charles A.
Assistant Examiner: Estremsky; Sherry Lynn
Attorney, Agent or Firm: Young & Basile, P.C.
Claims
The invention claimed is:
1. A shifter interlock for an automotive vehicle comprising:
a shifter including a shift lever mounted for movement in and out of a PARK
position;
electromagnetic means having a moveable armature and a shaft attached to
the armature for movement therewith to alternatively inhibit and enable
movement of the shift lever out of the PARK position according to the
energization state of the electromagnetic means;
an electrical power circuit connecting the electromagnetic means with a
vehicle power supply and including at least one switch for selectively
energizing and de-energizing the electromagnetic means;
an ignition switch having an OFF and an ON position and serving to move a
blocking means between a first position corresponding to the OFF position
of the ignition switch and a second position corresponding to the ON
position of the ignition switch, the blocking means in its first position
being inserted into the electromagnetic means and into motion inhibiting
contact with the armature to oppose movement of the shaft away from its
shift inhibiting position, and in its second position offering no
opposition to movement of the shaft.
2. The shifter interlock of claim 1 wherein the electromagnetic means
further comprises:
an electromagnet which when energized acts on the armature to hold the
shaft in the shift inhibiting position; and
a spring which urges the shaft toward the shift inhibiting position.
3. The shifter interlock of claim 2 wherein the shift lever and the shaft
are operatively associated such that when the electromagnet is in the
de-energized state, movement of the shift lever out of the PARK position
moves the shaft away from its shift inhibiting position.
4. The mechanism of claim 1 in which the electrical power circuit
comprises:
a brake circuit operative such that the electromagnetic means is
de-energized upon activation of a vehicle braking system.
5. A shifter interlock for an automotive vehicle comprising:
a shifter including a shift lever mounted for primary movement in and out
of a PARK position and a release movement for engaging and disengaging a
mechanical PARK detent;
a release member linearly movable between a first position in which it
inhibits shift lever release movement and a second position in which it
enables shift lever release movement;
electromagnetic means having a substantially rigid shaft movable between an
extended position wherein the shaft protrudes into dead bolt engagement
with the release member to inhibit movement of the release member to the
second position and a retracted position wherein the shaft is withdrawn
from engagement with the release member and movement of the release member
is not inhibited, the electromagnetic means holding the shaft in the
extended position when energized and permitting movement of the shaft to
the retracted position when de-energized;
an electrical power circuit connected with the electromagnetic means and
including at least one switch for selectively energizing and de-energizing
the electromagnetic means; and
an ignition switch mechanically associated with the electromagnetic means
to inhibit movement of the shaft to the retracted position when the
ignition switch is in an OFF position and to enable movement of the shaft
to the retracted position when the ignition switch is in an ON position.
6. The shift interlock of claim 5 wherein the ignition switch in the OFF
position inserts a blocking means into the path of movement of the shaft
to hold the shaft in the extended position, and in the ON position
retracts the block means from the shaft's path of movement to allow the
shaft to move to the retracted position.
7. The shift interlock of claim 6 wherein the ignition switch is mounted
immediately adjacent the electromagnetic means.
8. The shift interlock of claim 5 wherein the electrical power circuit
comprises a brake circuit operative such that the electromagnetic means is
de-energized upon activation of a vehicle braking system.
Description
FIELD OF THE INVENTION
This invention relates to shifter interlocks for automotive vehicles
equipped with automatic transmissions and more particularly to a shifter
interlock involving the combination of both electromagnetic and purely
mechanical controls.
BACKGROUND OF THE INVENTION
Operator manipulation of the automatic transmission of a motor vehicle is
typically accomplished by way of a shift lever mounted either on or near
the steering column of the vehicle or in or adjacent a console mounted on
the floor of the vehicle between the driver's seat and the front passenger
seat. The shift lever is mounted for primary movement between a PARK
position and the Forward and Reverse driving positions, usually separated
by a "Neutral" position. The shift lever is also mounted to provide a
release movement, usually at right angles to the primary movement, through
which a pawl is lifted out of and seated into a detent to hold the shift
lever in the PARK position and prevent inadvertent movement of the lever
in the primary mode; i.e., from PARK to one of the drive positions. The
release movement can be implemented in several ways including (a) lateral
shift lever movement, (b) fore-and-aft shift lever movement, (c) axial
shift lever movement, and (d) depression of a push button.
Beginning in about the late 1980's automobiles manufactured for sale and/or
use in the United States have been equipped with one of several types of
shift lever interlocks, the most typical being a solenoid-implemented
interlock which prevents the shift lever from being moved out of the PARK
position until the operator has activated the ignition circuit and
depressed the brake pedal. Depression of the brake pedal closes a switch
normally associated with the brake light circuit to either supply or cut
off the supply of power to a solenoid coil thereby to position an armature
connected pin. Depending on the particular implementation of the interlock
the solenoid pin can be used to latch either the shift lever primary
movement or the release movement.
The interlock, although commonly involving the brake light circuit, can be
associated with any automotive system capable of producing an appropriate
electrical signal; e.g., a seat belt switch or a seat occupancy switch.
Examples of such interlocks are illustrated in U.S. Pat. Nos. 4,854,193
and 4,986,399.
U.S. Pat. No. 4,887,702, assigned to United Technologies Automotive, Inc.,
discloses an interlock for a floor mounted shifter in which both a
mechanical ignition lock and a brake/shift lock solenoid are connected to
a pivotally movable PARK/LOCK member in the shifter by means of one or
more cables. According to the further disclosure of U.S. Pat. No.
5,027,929, also assigned to United Technologies Automotive, the cable
implemented interlock of U.S. Pat. No. 4,887,702 requires not only one or
two relatively expensive cables but also requires a relatively precise
cable length adjustment procedure during installation to ensure that the
solenoid will operate properly.
SUMMARY OF THE INVENTION
The present invention provides a shifter interlock using an electromagnet
to inhibit shifter operation until a specified condition, such as brake
pedal depression, is satisfied, wherein the movable armature of the
electromagnet is also mechanically tied to the vehicle ignition lock such
that the armature may not be moved to a shifter-operable position until
the ignition lock is released.
In general the invention comprises an automotive shifter having a shift
lever and an axially movable shift lever release member which is movable
between a first position in which primary shift lever movement is
prevented and a second position in which primary shift lever movement is
permitted. The axial or linear movability of the shift lever release
member is determined by an electromagnet which locks or releases the shift
release member according to the status of the specified condition. The
ignition key lock includes a bolt or pin extendable into contact with the
electromagnet armature to alternatively block and release movement of the
bolt in accordance with the condition or status of the ignition key lock.
As a result the purely mechanical ignition key/shifter interlock is
superimposed on the electromagnetic interlock so as to provide a multiple
condition interlock which can be implemented without cables and without
the complex installation procedures associated with cables.
In the illustrated embodiment the shift lever is steering column mounted
and both the ignition key lock and the electromagnet are conveniently
mounted on the steering column in close physical proximity so as to be in
direct association with the shifter release member. In the preferred form
the electromagnet holds a locking bolt in engagement with a notch in the
shift lever release member and the ignition key lock operates in the
manner of a bolt type lock to alternatively enable and inhibit movement of
the bolt away from engagement with the release member.
The preferred embodiment of the invention uses an electromagnet holding
device as opposed to the more conventional solenoid. In the latter device,
energization of an electrically conductive coil creates an electromagnetic
field which induces axial movement of a ferromagnetic core positioned
inside the coil. An electromagnet holding device, by contrast, comprises a
ferromagnetic canister which is magnetized when an electrically conductive
coil disposed therein is energized. A non-ferrous bolt or shaft is
slidingly mounted in a hole passing through the central axis of the
canister and a ferromagnetic armature disk is attached to one end of the
bolt. If the armature disk is in contact with the open end of the canister
when it becomes magnetized by the energization of the coil, the disk will
be held firmly in contact with the canister. If the disk is not in contact
with the canister when it becomes magnetized, however, insufficient
attractive force is exerted on the disk to draw it towards the canister.
Thus the electromagnet device serves a "holding" function as opposed to
the "pulling" function of the conventional solenoid.
A solenoid is usable in the present invention however a solenoid generally
has lower holding power than an electromagnet of comparable size and
weight. Consequently, a solenoid-based system would be larger and consume
more raw materials and more power in operation than an electromagnet-based
system. The relatively small size of the electromagnet-based system is
also particularly advantageous in this application.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partially cut away perspective view of the invention in
assembly with a steering column mounted shift control mechanism viewed
from the instrument panel more-or-less toward the driver;
FIG. 2 is a sectional view of the interlock device with the shift control
mechanism in PARK and the ignition switch in the Off position;
FIG. 3 is a sectional view of the interlock device with the shift control
mechanism in PARK and the ignition switch in the On position;
FIG. 4 is a sectional view of the interlock device with the shift control
mechanism moved out of PARK and the shift lever release member moved away
from its shift inhibit position;
FIG. 5 is a sectional view showing the gear position detents in the detent
plate; and
FIG. 6 is a schematic diagram of an electrical circuit for a brake/shift
interlock utilizing the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 illustrates a portion of an automotive vehicle steering column 10
carrying a shift lever 12 for an automatic transmission, not shown. The
shift lever 12 is conventional in operation, providing a primary motion
about the axis of a pivot pin 22 parallel to the steering column 10 to
shift the transmission between PARK and one of the conventional drive
positions. A PARK detent lock comprising a pawl 18 formed integrally with
the shift lever 12 and a detent plate 19 is engaged and released by a
shift lever release motion about the axis of a release pin 16 held in
bracket 14. The release movement, from the driver's vantage point,
involves pulling the shift lever upward toward the driver to release pawl
18 from the PARK detent in plate 19, after which the primary lever
movement is enabled.
Bracket 14 and shift lever 12 are mounted on a shifter housing 17 having a
cylindrical inner bore 23 running in a direction substantially parallel to
the longitudinal axis of steering column 10 and having an open end
adjacent shift lever 12. A shift lever release member 24 is mounted for
reciprocating linear movement in bore 23. A notch 44 is formed in the
member 24 between the opposite ends for purposes explained below. A bias
spring 26 is located at the lower end of inner bore 23 to urge release
member 24 into a position in which it bears against the lower end of shift
lever 12 in proximity with pawl 18. Spring 26, therefore, provides a bias
force operative on the release mode of the shift lever, which bias force
is easily overcome by the vehicle operator by pulling upward on shift
lever 12 to pivot it about release pin 16. Pulling upward on shift lever
12 pushes downwardly on member 24 to partially compress spring 26.
An electromagnet 28 is mounted on shifter housing 17 and is connected in
circuit with the vehicle electrical system (FIG. 6) by means of an
electrical connector 32. As can best be seen in FIG. 2, electromagnet 28
comprises a housing 40 for an open-ended, generally cylindrical canister
36 having an axial through bore 31 which is arrayed at right angles to the
axis of motion of release member 24. Canister 36 is made of a ferrous
material and has an annular pocket 33 formed coaxial with bore 31. A coil
30 of copper wire is wound on a spool 35 which fits inside pocket 33. An
armature disk 34 made of a ferrous material is fixed to a shaft 38 which
is slidably mounted in axial bore 31. A spring 42 is positioned inside
housing 40 to urge armature disk 34 and shaft 38 toward release member 24.
When coil 30 is energized as hereinafter described, the resulting
electromagnetic field magnetizes canister 36 so that disk 34 is held
firmly in contact with the open end surfaces of canister 36 as shown in
FIG. 2 such that release member 24 is held against significant movement in
either direction.
When armature disk 34 is in contact with canister 36, shaft 38 extends into
dead bolt engagement with notch 44. A chamfer 46 is preferably formed on
the left side of notch 44 and a bevel 39 is formed on shaft 38 such that
the two surfaces provide a cam action which forces shaft 38 downward when
release member 24 moves to the right (FIG. 2). When electromagnet 28 is
energized, however, it holds shaft 38 firmly in the extended position, so
that its engagement with notch 44 effectively locks release member 24 in
the position shown in FIG. 2. In this position, the shift lever 12 cannot
with normal operator effort be pulled toward the driver to release pawl 18
from the PARK detent. Because the shift lever cannot with normal effort be
released from the PARK detent, primary movement of the lever out of PARK
is effectively prevented.
A key operated ignition switch 48 of the type commonly used in automobile
ignition systems is mounted on shifter housing 17 adjacent electromagnet
28. Ignition switch 48 has an OFF position shown in FIGS. 1 and 2, and an
ON position shown in FIGS. 3 and 4. In the OFF position, a cam 49 pushes a
bolt pin 50 against the resistance of a compression spring 52 into housing
40 of electromagnet 28 where it prevents armature disk 34 from being moved
away from the position shown in FIG. 2 where the shaft 38 extends into the
notch 44 in release member 24. In the ON position, the bolt pin 50 is
retracted to permit the disk 34 and bolt 38 to move downwardly as shown in
FIG. 4.
Referring to FIG. 6, a circuit is shown to provide an interlock between the
braking system of a motor vehicle and the shifter shown in FIGS. 1-5. In
FIG. 6 a 12 volt automotive battery 60 is connected in series with
electromagnet coil 30 through ignition switch 48 and a normally closed
brake switch 64. When both switches 48 and 64 are closed, the coil 30 is
energized and the armature disk 34 is held in the position shown in FIG.
2. Switch 64 is connected to brake pedal 62 to be opened when the brake
pedal is depressed. Opening either of switches 48 and 64 de-energizes coil
30.
Operation
When the vehicle operator first enters the vehicle, shift lever 12 is in
the PARK position and ignition switch 48 is in the OFF position. In this
condition bolt pin 50 is extended to prevent movement of armature disk 34
away from release member 24. Even though there is no power to energize
coil 30, shaft 38 is mechanically held in notch 44. This engagement holds
release member 24 in the shift inhibit position in which it bears against
the lower end of shift lever 12 to hold pawl 18 in engagement with the
PARK detent. This configuration prevents the vehicle operator from
pivoting shift lever 12 about release pin 16 to disengage pawl 18 from the
PARK detent, so the shifter is locked in PARK.
When the operator moves ignition switch 48 to the ON position, bolt pin 50
moves to its retracted position in which it offers no opposition to
movement of armature disk 34 (see FIG. 3). Moving the switch 48 to ON,
however, also energizes electromagnet 28 so that armature disk 34 is
magnetically held against the face of canister 34 and shaft 38 is firmly
maintained in the extended position. The release movement of the gear
shifter continues to be inhibited. Because of the chamfered face of notch
44, the interlock can be overcome by the application of greater than
normal force to the shift lever 12.
When the operator depresses the vehicle brake pedal 62, switch 64 opens and
coil 30 is de-energized, thus removing the electromagnetic force that
holds shaft 38 in its extended position. When the operator pivots shift
lever 12 about release pin 16, release member 24 is relatively easily
pushed toward the position shown in FIG. 4 and the interaction between
bevel 39 and chamfer 46 forces shaft 38 to its retracted position. The
operator is now able to move shift lever 12 about pivot pin 22 and thereby
shift the transmission out of PARK.
In the preferred embodiment of the invention, bevel 39 and chamfer 46 are
shaped so that if the vehicle operator is pulling on shift lever 12 at the
time coil 30 is de-energized, the force being applied to release member 24
will not result in binding between notch 44 and shaft 38 that might
prevent movement of shaft 38 to its retracted position. This preload
release geometry is described in detail in U.S. Pat. No. 5,176,231, issued
Jan. 5, 1993 and assigned to Pontiac Coil, Inc. of Waterford, Mich., the
disclosure of said patent being incorporated herein by reference.
The mechanism as described provides another vehicle safety feature in that
ignition switch 48 can only be returned to its OFF position if shift lever
12 is first placed in PARK. This prevents the ignition key from being
removed from ignition switch 48 until the vehicle is stopped and the
transmission is in PARK.
An advantage of the mechanism described is that no sound audible to the
vehicle operator will be produced when the brake interlock is deactivated
by application of the vehicle brakes.
As is apparent from the above description and accompanying drawings, the
present shift interlock mechanism provides a simple, compact, and reliable
means by which to prevent a vehicle transmission shift lever form being
moved out of PARK and into a driving gear range until the ignition switch
48 has been placed to the ON position and the brake pedal 62 has been
depressed. The interlock mechanism adds a minimum of moving parts to the
shifter, and the integration of the ignition switch and brake interlocks
is executed so that the mechanism will easily fit inside of a steering
column.
It will be appreciated that the drawings and description contained herein
are merely meant to illustrate a particular embodiment of the present
invention and are not meant to be limitations upon the practice thereof as
numerous variations will occur to skilled persons. For example, the
interlock mechanism may be moved to the console in whole or in part.
Although the elimination of cables is advantageous, ignition lock 48 may
be connected to bolt pin 50 with a cable if a remote location is desired.
The coil 30 may be interlocked not only with a brake switch, but any
switch operable within the vehicle's electrical system.
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